Here's a quirk I'm experiencing in Win 8 with Power Management. I have my desktop set to go into sleep mode after an hour of inactivity. Display shuts off in 15 minutes. The display indeed goes dark as scheduled. But the disks never seem to follow suit. Even if I purposefully engage sleep mode the computer goes to sleep but later on I'll find it's back on.

I've scoured the internets and it seems to be a common problem. I've tried all suggested settings from various forums and blogs to no avail: Network card power options, Scheduled Tasks Timer, and various advanced settings in Power Management. I didn't have to do any funky setting adjustments when in Win7. I have a feeling this issue could have to do with Win 8's live tiles but not sure where to look to fix this.